We assessed the association between serum heat shock protein 27 (Hsp-27)concentrations in patients with acute coronary syndrome (ACS) and compared them with healthy participants. Patients with ACS (n = 75) were recruited and their biochemical parameters were compared with 75 healthy participants. Heat shock protein 27 concentrations were measured from blood samples taken on admission and 12 hours after the onset of chest pain. In the patient group, Hsp-27 concentrations (31.62 [20.12-38.51] ng/mL) in the first blood samples were significantly (P < .001) higher than in control samples (20.12 [16.67-28.17] ng/mL). In patients, serum Hsp-27 levels on admission were significantly (P < .001) higher than for the samples collected 12 hours after the onset of chest pain (25.87 [ 15.52-31.62]); the latter did not differ significantly from samples of healthy controls. In conclusion, serum Hsp-27 concentrations are elevated in the early hours following ACS, but fall to levels near to those in healthy individuals after about 12 hours from the onset of chest pain.